The purpose of this investigation is to analyze the acoustic changes that occur in the voice of patients who are undergoing radiotherapy for the control of laryngeal carcinoma. Sustained utterances and sentences are recorded from the speech of patients as they undergo radiotherapy treatment and at periodic intervals at the completion of this treatment. From the recorded samples of the speech of these patients, measures of fundamental frequency, pitch perturbation, overall sound pressure level, and the sound pressure level in 23 1/3 octava filter bands are determined. In addition, estimates of the patient's phonational and dynamic range are obtained. For purposes of comparison, speech samples from patients who are undergoing radiotherapy of the neck but in whom there is no laryngeal carcinoma are being obtained. Finally, speech samples from an appropriately matched age group of normal speakers are also obtained. The data obtained from this experiment will help to describe the nature of the acoustic change that takes place during radiotherapy.